Coil freeze protection device



May 16, 1967 A. NYIRI COIL FREEZE PROTECTION DEVICE Filed Oct. 16, 1964INVENTOR Laws 1. A/yw'o United States Patent 3,319,657 COIL FREEZEPROTECTION DEVICE Louis A. Nyiri, 120 N. Fairview St.,

Lock Haven, Pa. 17745 Filed Oct. 16, 1964, Ser. No. 404,295 1 Claim.(Cl. 13827) This invention pertains to heat exchange coils and moreparticularly to relief plugs for preventing damage when the fluid withina serpentine heat exchange coil freezes.

An object of the invention is to prevent damage to a heat exchange coilin the event the fluid within the coil freezes.

A further object is to provide a relief plug which will relieve stresscreated by a freeze-up within the coil.

A further object is to place a relief plug at the bends of a serpentinecoil to effectively relieve pressure caused by a freeze-up beginning inthe straight sections of the coil.

Further purposes appear in the specification and in the claim.

In a heat exchange coil of a type which may be used for either heatingor cooling, a fluid or vapor normally passes within a serpentinearrangement of tubing. Such liquids or vapors may be, for instance, inthe case of a heating system, hot water or steam, or in the case ofrefrigeration, any of the well known refrigerants such as Freon. Theserpentine tubing normally consists of straight sections and U-shapedend sections connected to two of the adjacent straight sections.

When used for heating, hot water or steam passes through the interior ofthe coil and air to be heated is blown over the exterior. The air isusually coming from a colder source, such as the exterior of a building,and there is a chilling effect on the coil. Sometimes the fluid withinthe coil freezes and causes the coil to burst. In a cooling coil, therefrigerant may likewise freeze under improper conditions causing damageto the coil.

Efforts have been made to relieve or to prevent such damage fromfreezing. In one form of protection against freezing used in the priorart, a temperature sensing device acts responsive to the temperature ofthe air which has been passed over the coil. When such air drops below acertain temperature, for instance, 36 or 38 degrees Fahrenheit, thedevice will close an outside air damper which prevents air from passingthrough the exchanger. The device can additionally open a control valvein the coils to allow full flow through the coil, and it canadditionally shut down the fan motor blowing air across the coil. Inspite of such precaution, however, coils still freeze and burst.

In the present invention, it has been found that freezing takes place inthe coils in the center part of the straight sections and travels to theend connections or U connections. It has been further found that byrelieving the pressure at the bend of the coil, damage to the coil fromfreezing can be prevented.

The present invention does not attempt to prevent freezing in aserpentine coil but rather prevents damage to the system when freezingoccurs. This is done by providing relief plugs in the bends of the coil.The relief plug is secured in a housing which is desirably integral withthe coil itself. The plug includes a plug body which holds a disc that,in the event of freezing, is forced out of the plug body and relief isallowed for the expanding solid, for instance, ice. Hence, there is nodamage to the coil itself and the relief plug or disc can be readilyreplaced.

In the drawings I have chosen to illustrate a few only of the numerousembodiments in which the invention may appear, selecting the forms shownfrom the standpoints of convenience in illustration, satisfactory opera-3,319,657 Patented May 16, 1967 ICC tion, and clear demonstration of theprinciples involved.

FIGURE 1 is a fragmentary front elevational view of a typical serpentinecoil showing several embodiments of the invention.

FIGURE 2 is a fragmentary vertical sectional view of the relief plug ofFIGURE 1.

FIGURE 3 is an end elevation of the relief plug of FIGURE 2.

FIGURE 4 is a vertical section of an alternate embodiment of a reliefplug.

FIGURE 5 is a sectional view of an alternate embodiment of a reliefplug.

Describing in illustration but not in limitation and referring to thedrawings:

As seen in FIGURE 1, a serpentine coil 20 of tubular construction hasstraight sections 22, 24, 26 and 28 and U-bends 30, 32 and 34 joiningthe adjacent straight sections. The coil '20 may be formed of anysuitable material, such as copper, which has a sufliciently high rate ofthermal conductivity to readily permit a heat exchange through thetubing. It will be understood that only a portion of a coil is shown,and that the coil may permissibly have any number of bends and may be ofany size and proportion.

The U-bends are suitably connected, as by soldering, at joints 36, 38,40, 42, 44 and 46. These joints can be of a type having a flared section48 on the U which receives therein the end of the straight section, withsolder connecting and holding fast the flare and the portion of thestraight tube within the flare, where the tubing is of, for instance,copper.

The relief means of the invention may be applied to the coil in avariety of embodiments. In one embodiment as shown at 50 in U-bend 30 asseen in FIGURE 1, housing 52 is integrally connected to the U connectionand includes a tubular portion 54 which is in line with straight section22. The main portion of the housing 52 comprises a portion 56 which hassuitably located therein internal threads 58.

Plug body 60, having threads 62, is screwed into housing portion 56. Theplug additionally includes a disc 64 which engages in cut-out portion 66of the plug body 60 by means of, for instance, a shrink fit which can beachieved by expanding the plug body 60 by heat means, inserting the discwithin the plug body in the cut-out portion 66, and then allowing theplug body 60 to cool, thus securely holding the disc.

The housing 52 along with the plug body 60 and disc 64 may be positionedalternatively at the base or bend of the U-bend as shown in itsinstallation in the U-bend 32 at 70. In this embodiment, the tubularportion 54 is formed into the bend at a point intermediate the straightsections 24 and 26.

In another form, as shown in the U-bend 34 in FIG- URE l, housings forthe plugs are formed at 74 and 76 which are extensions of the straightsections 26 and 28. The form of these plugs is the same as that shown at50 in FIGURE 1.

Alternative fonms of plugs are shown in FIGURES 4 and 5. In FIGURE 4, ahousing 80 in the form of a sleeve has a tubular portion 82 and a flaredportion 84. The tubular port-ion 82 is joined by soldering or the liketo section 86 which extends from U-bend 88. The flared portion 84supports therein a disc 90 having a skirt 92. The skirt 92 is held inthe sleeve by means of a shrink or force fit.

In the form shown in FIGURE 5, the relief plug is in the form of a body94 having a portion 96 ending in a flat face 98. A smooth flat disc 100is secured to the face by means of an adhesive or cohesive type materialwhich will break under a predetermined pressure. The

3 body has a tubular portion 102 which is secured to extension 194 ofU-bend 106. V

In operation, the coil is assembled with any of the plugs as showninstalled in the U-bends of the coil. In the event the fluid Within thecoil begins freezing, a solid begins forming in the straight. sections22, 24 and 26 at generally the centers thereof and moves progressivelytowars the bends. As long as there is space for the solid, formed byfreezing, to expand in any direction, no damage to the coil tubingoccurs. When the freezing action of the fluid into a solid progresses tothe U-bends, there is no more space for expansion. However, the actionof the expanding, freezing, fluid forces the disc 64 out of the plugbody 60, thus relieving the pressure Within the coil 20 without damageto the coil itself. The plug can then be readily replaced with areplacement plug or a replacement disc.

In view' of my invention and disclosure, variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of myinvention without copying the structure shown, and I, therefore, claimall such insofar as they fall within the reasonable spirit and scope ofmy claim.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

In a heat exchange coil ,of serpentine form having straight sections andU-bends connecting the straight sections, relief means'in the U bendsfor relieving pressure caused by fluid within the coil freezing into asolid comprising a housing mounted in the U-bend and communicatingWiththe interior of the coil and a plug supported by the housing havinga plug body held by the housing and a disc in the plug body adapted tobe separated from the plug body by the pressure of the freezing solid.

References Cited by the Examiner UNITED STATES PATENTS 1,159,22511/191-5 Howell 13827 FOREIGN PATENTS 560,612 4/194'4 Great Britain.

LAVERNE D. GEIGER, Primary Examiner.

C. L. HOUCK, Assistant Examiner.

